Reese Witherspoon's birthday and what better way to celebrate than with some throwback pics! Jennifer Aniston, Laura Dern and Mindy Kaling are just a few of the celebrities wishing the Oscar winner a happy 45th birthday.Witherspoon's co-star shared an adorable photo of the birthday girl from grade school, calling Witherspoon her «sister.»«Who knew this would become one of the most extraordinary women ever, and my sister.